are you using the same app server as in the Oreily book? since (it sounds like) your client is external to the container, there's no standard way to access the transaction manager (per section 24.2.4 of the 2.0 spec, the UserTransaction is only gauranteed available, via the 'java:comp/UserTransaction' key, to bmp beans within an ejb container). however, app servers will generally publish a transaction manager in jndi for use by external clients. check your app server documentation for the client UserTransaction (or transaction manager) key, then point the initial context to the app server's jndi directory and look it up.

try con.lookup("java:comp/UserTransaction");